1. Field of Invention
This invention relates to tethered objects which can swivel, particularly to a tethered cap for a fluid container, which cap can swivel or rotate freely.
2. Description of Prior Art
In many applications there is a need to interconnect separate members so that they can swivel freely. The most common application is a liquid container and its cap: the cap should be able to swivel freely so that it can be screwed onto its container, yet should be held by a flexible tether so that it cannot be lost or misplaced. Another application is found in multi-part toys or disconnectable industrial or military assemblies which must be held together by a tether (so that they will not be lost) which should not be twistable (so that it will not tangle or wear).
Heretofore many different arrangements were used to interconnect separate members so that they could swivel freely. The following is a discussion of these arrangements and their drawbacks:
One type involved captivated cords which connected one object, such as a container cap to another, such as a container. Alexander U.S. Pat. No. 79,536, 1868, is examplary. However in these arrangements the cord was fixed in a non-swivelable manner at each of its ends so that the cap could swivel only to a limited extent, in accordance with the flexibility or twistability of the cord. This is undesirable since twisting the cord tended to wear it out prematurely and also caused it to kink and knot. Also it is desirable to have a tether which is infinitely swivelable (i.e., one where the cap can be rotated an infinite number of times) so that the tether can be made shorter and so that the tether does not have to be pretwisted before screwing on the cap. (If a non-swivelable tether is not pretwisted, it will become awkwardly twisted after the cap is screwed on.)
Another arrangement, shown in Klee U.S. Pat. No. 8,034, 1878, comprised a flexible tether which was passed through a horizontal hole in the cap and/or the container and was captivated by an enlarged stop at either or both of its ends. This type of tether was disadvantageous because a cap usually has to be twisted on a vertical axis to be screwed on; thus the horizontal hole(s) did not permit the right type of swiveling. Also the enlarged stop was not held in place and thus tended to extend out from the cap or container where it interfered with usage of the container.
In still another type, shown in Doyle U.S. Pat. No. 281,719, 1879, the cap had awkward top and side holes with tethers. The holes did not communicate and were difficult to use.
Boynton/Fravel U.S. Pat. No. 602,822, 1898, shows a stopper held by captivated rings and beads which were snapped into an elastic matrix. This of course did not permit swiveling and the snap-in beads were not reliable.
Copper U.S. Pat. No. 1,611,852, 1926, and Clemens U.S. Pat. No. 2,263,798, 1941, show beaded wires with the end beads snapped into position. While permitting infinite swiveling, the snap-in captivation of the beads was unreliable and relatively expensive.
Johnson U.S. Pat. Nos. 2,322,805 and 2,468,758, 1943 and 1949 employed a linked or flexible tether with an end stop which was captivated by passing it through a hole in a bar and welding the bar in place. While permitting infinite swiveling, this method was expensive and was not suitable for plastic parts.
Italian Pat. No. 498,610, 1954 and Berry U.S. Pat. No. 2,854,789, 1958, show a cap or other tethered part with a through hole where a flexible tether extended through the hole; the tether had an end stop on the inside of the cap, inside the container, or on the distal side of the tethered part. Since this type of captivation allowed the hole to communicate with the interior of the container, it could not provide a watertight seal. Katzman/Gordon U.S. Pat. No. 3,874,570, 1975, shows a tether with an enlarged end which was inserted into a side, partial circumferential, groove in a cap. This type of tether did not permit infinite swiveling and was unreliable.
Sherman/Francis U.S. Pat. No. 4,432,120, 1984, employed a bead chain or other flexible tether where end stops were captivated in laminated mounting ends which were attached to the cap and contained, respectively. This arrangement was difficult and expensive to fabricate and assemble and was unreliable in operation.